1. Field of the Invention
This invention relates to mortise locks with multiple functions in which the functions can be changed without opening the case.
2. Description of Related Art
Mortise locks need to provide a variety of functions. For example, in some installations it is desirable to disable rotation of the outside handle while allowing the inside handle to operate normally. In other applications, it is desirable to disable permanent unlocking of the handles with the key, or to disable retraction of the latch with the key. Making these changes to the normal operation of the mortise lock has previously required partially or totally disassembling the mortise lock and rearranging or configuring the mortise lock components to achieve the desired mode of operation.
Although such changes can be made reliably by trained personnel at the factory, the task of disassembling the mortise lock is still a relatively time consuming process. Moreover disassembling the mortise lock provides opportunities for damaging the components. Additionally, components may become lost during the adjustment process. These problems are accentuated when the changes need to be made in the field by installers or maintenance personnel.
A related problem is that there are often many different functions that can be provided. These functions are typically identified by a code or function number. However, once the mortise lock case has been opened, the installer must reference one or more drawings by function number to determine the correct internal change or changes to be made. There are many opportunities to make a mistake in this process.
After internal changes have been made, the reassembled mortise lock may appear identical to the original unmodified lock. This causes problems with identifying the modified locks when multiple mortise locks are being changed or installed with different functions.
When changes are to be made to a mortise lock, modified components may be necessary. This causes difficulties if the modified components are not readily available in the field. Conversely, when a previously modified lock is to be changed to the original functionality, any previously removed components must be replaced. This is a concern because the original components are often no longer with the lock and may have become lost.
To avoid the difficulties described above, most mortise lock manufacturers modify the locks only at the factory, and do not recommend or support modifications made in the field. This policy, however, requires that the manufacturer and its distributors stock mortise locks for all the different functions offered even though the locks are substantially similar in most respects. Stocking multiple mortise locks is expensive, particularly for the less common mortise lock functions. To reduce inventory costs, some locks that provide less common functions may not be stocked by distributors, resulting in ordering delays.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a multi-functional mortise lock in which the housing does not have to be opened in order to change lock functionality.
It is another object of the present invention to provide a multi-functional mortise lock in which multiple functions are marked on the exterior of the mortise lock adjacent to critical locations where changes are made to identify the functions performed by the lock once the changes have been made.
It is a further object of the present invention to provide a multi-functional mortise lock in which the functions performed by a modified mortise lock may be readily determined from the exterior of the mortise lock without opening the mortise lock case.
A further object of the present invention is to provide a multi-functional mortise lock in which the components required to modify the lock and to change the lock back to original functionality are kept with the lock in externally accessible locations.
Another object of the present invention is to provide a multi-functional mortise lock that can easily be changed between different functions by untrained personnel to reduce the number of different types of mortise locks providing different functions that would otherwise have to be stocked in a distribution chain.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.